Evaluation of prevalence and pattern of Fluorescent Antinuclear Antibodies(FANAs) among patients suffering from three major rheumatic diseases in Birjand, South Khorasan, Iran (۲۰۱۷-۲۰۱۹)

Background and Objective: Autoimmune diseases are defined as types of diseases with tissue destruction or organ dysfunction that occur due to an autoimmune mechanism. The rate of complications, mortality and health-care costs of autoimmune diseases is increasing. Antinuclear autoantibodies (ANAs) are antibodies that attack proteins inside the cell nucleus. Fluorescent antinuclear antibodies (FANAs) test involves viewing fluorescent-labeled antibodies on a glass slide under microscope and determining pattern and intensity of the fluorescence. This study aimed to examine the demographic information and risk factors of patients with ۳ most common autoimmune diseases including Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) and Sjogren's Syndrome (SS), and to investigate prevalence and pattern of FANA titers among patients referred to Birjand Rheumatology Clinic between ۲۰۱۷-۲۰۱۹.Materials and Methods: This cross-sectional study was performed on ۱۳۸ patients with confirmed diagnosis, according to American College of Rheumatology (ACR) criteria, of ۳ major rheumatic diseases including SLE, RA, and SS who were referred to the laboratory for ANA testing and had an ANA test report. Evaluation of ANA was performed by semiquantitative immunofluorescence method using commercial kit (IIFT Mosaic: HEp-۲/Liver (Monkey), Euroimmune, Germany). All patients diagnosed by a rheumatologist; individuals who had at least one of ۳ most common diseases, were included into the study. Patients without one of these ۳ diseases were excluded. In the first stage, each patient's serum was evaluated with ۱/۱۰۰ and ۱/۲۰۰ dilutions, and if the result was strong positive, the next dilutions included ۸۰۰, ۱۲۰۰, ۱۶۰۰, ۲۰۰۰, ۳۰۰۰, ۴۰۰۰, ۵۰۰۰, ۶۰۰۰, ۸۰۰۰, and ۱۰۰۰۰ were examined, respectively. Demographic information and history of diseases as well as related risk factors were collected by a questionnaire. Patients’ information was entered into SPSS (۱۶). Normal distribution was checked with Kolmogorov-Smirnov test.Findings: A total of ۱۳۸ individuals (mean age: ۴۵.۵ ± ۱۲.۹ years old, male/female ratio: ۰.۰۷) were enrolled in this study. Prevalence of SLE, RA, and SS was ۴۵.۵%, ۳۹.۰%, and ۱۵.۴%, respectively. The highest co-incidence was found between RA and SLE (۵.۸%), and the lowest co-incidence was found between SS and RA (۱.۴%). Overweighting was the most common risk factor, which was present in ۵۳.۶%, ۶۰.۴% and ۷۸.۹% of SLE, RA and SS patients, respectively. The positivity rate of FANA test was ۷۱.۴%, ۴۳.۸%, and ۷۸.۹%, with median titers of ۷۵۰, ۱۲۰۰, and ۱۶۰۰ in SLE, RA and SS, respectively. Conclusion: SLE was the most common rheumatic diseases, but SS had the highest rate of FANA positivity. The majority of patients suffered from being overweight. Prevalence of these ۳ diseases was higher in women. Middle-aged people were at higher risk than the others, and the incidence age of SLE was the lowest

Keywords:

fluorescent antinuclear antibody , FANA , systemic lupus erythematosus , rheumatoid arthritis , Sjogren's syndrome , prevalence , pattern